A secure and reliable method of probing many different signals simultaneously and feeding them back to a logic analyzer or oscilloscope is required to acquire the desired data from a Device Under Test (DUT). Conventionally, there are two options for probing in this way. The first option is to design into the DUT, a logic analyzer or oscilloscope connector or land pattern, at a specific location. This connector or land pattern interfaces with a logic analyzer or oscilloscope probe. This can be problematic if the traces must detour from their natural path to this location, because such a detour adds signal loss to the circuit being tested. This approach also reduces the flexibility of the layout design and occupies valuable circuit board space.
The second option is to attach the logic analyzer or oscilloscope probes to existing component leads. However, newer and emerging circuit board technologies, such as surface mount components and ball-grid-array components, reduce the number of available leads to which a logic analyzer or oscilloscope probe may be attached. These technologies can even “hide” all potential test points completely, making it impossible to attach the logic analyzer or oscilloscope probes anywhere on the circuit board.
For applications where a convenient test point is accessible, a third option most commonly applied to oscilloscopes is the original hand-held probe. This method keeps a user's hand occupied during probing and relies on an individual's manual dexterity to keep the probe placed in the right location while visual attention is focused on data from the oscilloscope. Because of the human intervention in this process, the connection is not as secure and reliable as it could be.
When none of the conventional options can be utilized, one of the few remaining options for probing a test point is to attach a logic analyzer or oscilloscope probe to vias in the DUT. However, vias are small features, which makes it difficult to retain a logic analyzer probe within a via during a test. A via is a vertical electrical connection between different layers of conductors in a printed circuit board. It consists of two or more pads, in corresponding positions on different layers of the board, which are electrically connected by a cylindrical hole drilled through the board. The hole is made conductive by electroplating, or is lined with a conductive tube or a rivet.
Therefore, there is a need for a probe that retains itself in a via of a Device Under Test (DUT).